BARIDIIDAE 



25 



Length, 0.85 mm; height, 0.49 mm; 

 thickness, 0.38 mm. 



Renault formation, locality 13, common. 



This species may be distinguished by its 

 flat, almost parallel sides. 



Bairdia attenuata Girty 



Plate 1, figures 33-34 



Bairdia attenuata Girty, 1910, Ann, New York 

 Acad. Sci., vol. 20, p. 237, Fayetteville shale. 



Carapace very long and thin; central 

 portion of ventral margin almost straight, 

 upturned strongly to meet ends; anterior 

 extremity rounded, posterior produced to 

 sharp point directed slightly upward ; ex- 

 tremities slightly belov^^ middle; dorsum 

 convex in middle, sloping towards ends ; 

 postero-dorsal slope very low (35-40°). 



Length, 1.0 mm; height, 0.46 mm; thick- 

 ness, 0.29 mm. 



Glen Dean formation, locality 1, 

 common. 



Although no figures of the type from the 

 Fayetteville shale of Arkansas have been 

 published, the Glen Dean form, by com- 

 parison with the holotype, is so close to it 

 that there is little uncertainty concerning 

 this identification. 



Bairdia brevis Jones and Kirby 



Plate 1, figures 11-12 



Bairdia hre'vis Jones and Kirkby, 1867, Trans. 

 Geol. Soc. Glasgow, vol. 2, p. 221; 1879. 

 Geol. Soc. London, Quart. Jour., vol. 35, 

 p. 575, pi. 31, figs. 1-8. Carboniferous of 

 Great Britain. — Latham, 1932, Trans. Roy. 

 Soc. Edinburgh, vol. 57, pt. 2, p. 377, Car- 

 boniferous of Scotland. 



Carapace high and thick ; strongly con- 

 vex, dorsum highly arched, forming extrem- 

 ely long postero-dorsal slope inclined about 

 45°; posterior point very low, venter 

 straight in middle and curved to meet ends ; 

 surface granulose. 



Length, 1.0 mm; height, 0.60 mm; 

 thickness, 0.43 mm. 



Menard formation, locality 15, common. 



Bairdia cestriensis Ulrich 

 Plate 1, figures 27-28 



Bairdia cestriensis Ulrich, 1891, Cincinnati Soc. 

 Nat. Hist, Jour., vol. 13, p. 210, pi. 17, figs. 

 6a-c, Chester series. — Girty, 1915, U. S. Geol. 

 Survey, Bull. 595, p. 39, pi. 2, fig. 10, Bates- 

 ville sandstone. 



Bairdia cestriensis granulosa Girty, 1910, Ann. 

 New York Acad. Sci., vol. 20, p. 237, Fayette- 

 ville shale. 



Bairdia cooperi Croneis and Gale, 1939, Bull. 

 Denison Univ., Jour. Sci. Lab., vol. 33, p. 

 287, pi. 6, figs 11, 12, Golconda formation. 



Length, 1.45 mm; height, 0.73 mm; 

 thickness, 0.58 mm. 



Renault formation, locality 12, abundant; 

 Golconda formation, locality 19, abundant; 

 Glen Dean formation, locality 1, rare; Men- 

 ard formation, locality 7, rare. 



This species presumably described from 

 the Glen Dean limestone near Grayson 

 Springs, Kentucky, appears to be identical 

 with forms found in the Renault, Golconda, 

 Glen Dean, and Menard formations in the 

 Illinois Chester and the lower Fayetteville 

 of Arkansas. The granulose surface of 

 Girty's specimens appears to be due to the 

 character of the preservation. 



Bairdia curvis Cooper, n. sp. 

 Plate 1, figures 43-44 



Carapace elongate, tumid ; ends rounded ; 

 dorsum arched, meeting anterior margin in 

 smooth curve, posterior slope 45°, venter 

 strongly concave, giving entire shell a de- 

 cidedly bowed appearance. 



Length, 1.14 mm; height, 0.46 mm; 

 thickness, 0.41 mm. 



Paint Creek formation, locality 32, depth 

 1304-1343 feet, common. 



This species lies between B. hisingeri 

 (Miinster) and B. suhelongata Jones and 

 Kirkby; it is shorter and more rounded on 

 the ends than the former; and higher and 

 more bowed than the latter species. It is 

 known only from the Golconda and Paint 

 Creek formations from the wells in Muh- 

 lenberg County, where it is found associated 

 with two species of Bythocypris. 



Bairdia delicata Morey 



Plate 1, figures 45-46 



Bairdia delicata Morey, 1935, Jour. Paleontology, 

 vol. 9, p. 480, pi. 54, figures 14, 16, Amsden 

 formation. 



Carapace elongate, tenuous ; overlap most 

 prominent along dorsal and ventral mar- 

 gins; venter straight, dorsum curving 

 almost equally toward each end, anterior 

 curve slightly more abrupt; antero-dorsal 

 slope somewhat pronounced, forming angle 

 at junction with anterior margin; posterior 

 slope low (about 45°). 



Length, 0.71 mm; height, 0.31 mm; 

 thickness, 0.24 mm. 



Menard formation, locality 20, common. 



